An approaching upper-level low pressure system resulted in strong, gusty westerly/northwesterly winds in the mountains and through the passes and canyons. Typical with these events, the strongest winds were through the Banning Pass and nearby canyons.
Every event with a place to put it; 2 filed by county or forecast zone are drawn at its center, in a lighter ring. Tap one for its entry below.
Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
The episode as NWS SGX wrote it up.
An approaching upper-level low pressure system resulted in strong, gusty westerly/northwesterly winds in the mountains and through the passes and canyons. Typical with these events, the strongest winds were through the Banning Pass and nearby canyons.
The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS San Diego, CA wrote its last area forecast discussion before the first event at May 17, 12:25 PM PST, 35 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SAN DIEGO CA 125 PM PDT THU MAY 17 2012 .SYNOPSIS... AN APPROACHING LOW PRESSURE TROUGH WILL BRING STRONG AND GUSTY WESTERLY WINDS THROUGH AND OVER THE MOUNTAINS...AND INTO THE DESERTS LATE THIS AFTERNOON AND TONIGHT. THE STRONG ONSHORE FLOW WILL DEEPEN THE MARINE LAYER...AND PUSH LOW CLOUDS...FOG AND PATCHY DRIZZLE WELL INLAND BY FRIDAY MORNING. IT WILL BE MUCH COOLER FRIDAY...THEN GRADUAL WARMING THROUGH THE WEEKEND WITH A SHRINKING MARINE LAYER AND ASSOCIATED CLOUDS AS HIGH PRESSURE REBUILDS ALOFT. DRY WITH TEMPERATURES ABOVE AVERAGE EARLY NEXT WEEK...BUT SOME COOLING IS EXPECTED AFTER MONDAY AS ANOTHER UPPER-LEVEL TROUGH DEVELOPS OVER THE AREA. && .DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE... SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO COUNTIES... MARINE STRATUS DID NOT CLEAR THE SAN DIEGO AND COUNTY COAST TODAY. A COASTAL EDDY AND INCREASING ONSHORE FLOW SHOULD KEEP THE CLOUDS INTACT AND START THEM MOVING FARTHER INLAND BY LATE AFTERNOON. SURFACE PRESSURE GRADIENTS WERE TRENDING STRONGLY ONSHORE WITH OVER 8 MBS AT NOON TO NV. WINDS WERE INCREASING OVER THE MOUNTAINS WITH GUSTS OVER 20 MPH IN MANY AREAS...AND OVER 40 MPH THROUGH THE BANNING PASS. MAIN FORECAST PROBLEM FOR THE NEXT 12-24 HOURS WILL BE THE WESTERLY WINDS. THE WATER VAPOR LOOP SHOWS A WELL DEFINED TROUGH MOVING THOUGH NOCAL AT MIDDAY IN AGREEMENT WITH THE MODELS. THIS TROUGH IS FORECAST TO DEEPEN AS IT MOVES INLAND THROUGH THE GREAT BASIN...DROPPING SFC PRESSURES AND DRIVING INCREASING ONSHORE FLOW OVER SOCAL. LOCAL WIND GUIDANCE AND MODELS INDICATE WIND GUSTS IN EXCESS OF 30 TO 40 KTS DEVELOPING OVER THE WIND PRONE MOUNTAIN CRESTS AND SLOPES...AND THROUGH THE BANNING PASS INTO THE DESERTS BY LATE AFTERNOON/EARLY EVENING. SOME GUSTS IN ISOLATED SPOTS WILL LIKELY PEAK NEAR 60 MPH OR MORE OVERNIGHT. A HIGH WIND WARNING HAS BEEN ISSUED FOR NORTHERN PORTIONS OF THE COACHELLA VALLEY WITH WIND ADVISORIES ELSEWHERE. SEE LAXNPWSGX. ASIDE FROM THE WINDS...IT WILL BE MUCH COOLER ON FRI...AND THERE MAY BE SOME DRIZZLE IN THE MORNING. BUT THE TROUGH WILL MOVE EAST QUICKLY AND HEIGHTS/THICKNESS WILL REBOUND THROUGH THE WEEKEND AS A WEAK SHORT-WAVE RIDGE DEVELOPS OVER CA AHEAD OF THE NEXT UPPER TROUGH. TEMPS WILL REBOUND TO ABOVE NORMAL LEVELS INLAND...WHILE THE MARINE LAYER AND ONSHORE FLOW KEEP A LID ON TEMPS OVER COASTAL AREAS. 12Z MODELS ARE IN GOOD AGREEMENT THROUGH MON...BUT BEGINNING TO DIVERGE AFTER THAT. BY MIDWEEK...THE GFS MODEL INDICATES A DEEPER UPPER TROUGH OVER THE GREAT BASIN...WHILE THE ECMWF SHOWS NEARLY ZONAL FLOW. EITHER WAY...THE WEATHER STAYS DRY HERE AND TEMPS SHOULD BE SLIGHTLY ABOVE SEASONAL AVERAGES THROUGH THU. BY THE END OF THE WEEK...THE DISCREPANCIES ARE MUCH BIGGER WITH THE ECMWF SHOWING AN ANOMALOUSLY DEEP TROUGH...WHILE THE GFS HOLDS A FLAT RIDGE OVER THE AREA. AT THIS POINT...WOULD BE INCLINED TO FOLLOW THE GFS LEAD CLOSER TO CLIMO. && .AVIATION... 172000Z...COAST/VALLEYS...A COASTAL EDDY IS KEEPING BKN-OVC STRATUS...BASES 1000-1200 FT MSL WITH HAZE...CLINGING TO THE IMMEDIATE COAST WITH CIGS PERSISTING AT KSAN AND KCRQ BUT BECOMING SCT AT TIMES THROUGH THE AFTERNOON. LOW CLOUDS WILL SPREAD BACK INLAND AS EARLY AS LATE AFTERNOON...THOUGH TIMING IS SOMEWHAT UNCERTAIN. BASES ARE EXPECTED TO BE 1500 TO 2000 FT MSL...LIFTING SOMEWHAT AND SPREADING INLAND TO THE LOWER COASTAL MTN SLOPES OVERNIGHT...REACHING KONT AFTER 18/09Z. STRATUS SHOULD CLEAR INLAND BY 18/16-17Z BUT REMAIN BKN-OVC NEAR THE IMMEDIATE COAST SIMILAR TO TODAY. MTNS/DESERTS...SOUTHWEST TO WEST WINDS WILL INCREASE THIS EVENING THROUGH EARLY FRIDAY MORNING...STRONGEST ALONG THE RIDGETOPS AND DESERT SLOPES OF THE MTS. SFC WIND GUSTS 35 TO 45 KT AND ASSOC UDDFS...LLWS...AND ROTOR ACTIVITY ARE POSSIBLE. OTHERWISE...FEW-SCT CLOUDS AOA FL200 AND UNRESTRICTED VIS THROUGH FRIDAY. && .SGX WATCHES/WARNINGS/ADVISORIES...WIND ADVISORY FOR MTNS...EXCEPT SANTA ANAS...AND DESERTS FROM 3 PM TODAY TO 6 AM FRIDAY...SEE LAXNPWSGX. && PUBLIC...JAD AVIATION...TS
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE SAN DIEGO CA 200 AM PDT THU MAY 17 2012 CAZ042-043-048-050-055>058-060>062-PZZ750-775-180000- ORANGE COUNTY COASTAL AREAS-SAN DIEGO COUNTY COASTAL AREAS- SAN BERNARDINO AND RIVERSIDE COUNTY VALLEYS-THE INLAND EMPIRE- SAN DIEGO COUNTY VALLEYS-SAN BERNARDINO COUNTY MOUNTAINS- RIVERSIDE COUNTY MOUNTAINS-SANTA ANA MOUNTAINS AND FOOTHILLS- SAN DIEGO COUNTY MOUNTAINS-APPLE AND LUCERNE VALLEYS- COACHELLA VALLEY-SAN DIEGO COUNTY DESERTS- COASTAL WATERS FROM SAN MATEO POINT TO THE MEXICAN BORDER AND OUT 30 NM- WATERS FROM SAN MATEO POINT TO THE MEXICAN BORDER EXTENDING 30 TO 60 NM OUT INCLUDING SAN CLEMENTE ISLAND- 200 AM PDT THU MAY 17 2012 THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF EXTREME SOUTHWESTERN CALIFORNIA. .DAY ONE...TODAY THROUGH TONIGHT AN APPROACHING TROUGH WILL BRING STRONG GUSTY WINDS LATE TODAY THROUGH TONIGHT TO THE MOUNTAINS AND DESERTS. WINDS WILL BE WESTERLY 20 TO 30 MPH WITH LOCAL GUSTS OVER 50 MPH. WINDS WILL BE STRONG ALONG INTERSTATE 10 EAST OF BANNING PASS AND ALONG INTERSTATE 8 IN SOUTHEASTERN SAN DIEGO COUNTY. .DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME. .SPOTTER INFORMATION STATEMENT... SKYWARN WEATHER ACTIVATION IS NOT REQUESTED FOR THIS AREA... HOWEVER WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER CONDITIONS. MAXWELL
The national radar mosaic for the moment the first event began.
2 high wind. Local standard time, as filed.
Winds first gusted over 45 mph at the Burns Canyon RAWS around 1300 PST on the 17th and continued through 0100 PST on the 18th. The peak gust of 76 mph occurred around 2100 PST on the 17th.
Winds first gusted over 45 mph at the Sky Valley mesonet around 1600 PST on the 17th and continued through 1200 PST on the 18th. The peak gust of 74 mph occurred around 0000 PST on the 18th.
Winds first gusted over 45 mph at the Whitewater RAWS around 1800 PST on the 17th and continued through 0800 PST on the 18th. The peak gust of 63 mph occurred around 2200 PST on the 17th.
Winds first gusted over 45 mph at the Edom Hill mesonet around 1800 PST on the 17th and continued through 0900 PST on the 18th. The peak gust of 55 mph occurred around 0800 PST on the 18th.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in California in 2012Every state in 2012This day in weather historyWarnings in California, May 2012
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 382511, 382510.